The present invention is directed to bicycles and, more particularly, to a derailleur used to shift a chain among a plurality of sprockets.
Bicycles are used both for general transportation as well as many recreational activities. Sometimes the bicycle is transported to locations away from home before being ridden. As a result, in recent years bicycles have been developed to make them more compact to facilitate transportation and ease of use, for example, but without losing functionality expected of bicycles. This includes the development of bicycles that have smaller wheels than those found on conventional bicycles.
Many bicycles currently available have multiple speed transmissions that allow the rider to select gear ratios to accommodate changes in running conditions. Such transmissions sometimes include a derailleur for transferring a chain among a plurality of sprockets. For example, a rear derailleur may be detachably fixed to the back end of the bicycle frame, wherein the rear derailleur engages a chain on any one of a plurality of sprockets that are rotatably mounted on the rear wheel hub. One such derailleur is disclosed in Japanese Unexamined Patent Application Number 8-188852. The rear derailleur taught in that publication comprises a base member disposed on a rear end of the bicycle frame, a four-point link mechanism disposed on the base member, and a chain guide disposed on the four-point link mechanism. When this rear derailleur is operated, the four-point link mechanism moves the chain guide laterally onto any one of a plurality of sprockets mounted to the rear wheel axle.
When a conventional derailleur is mounted on a small-wheeled bicycle, there is a risk that the rear derailleur may come into contact with the road surface when the bicycle is inclined either when the bicycle is stopped or during riding. While this does not pose a problem in terms of rear derailleur function, the surface of the rear derailleur may become damaged and the appearance of the rear derailleur suffers.